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A Roadmap To Net-Zero Water

By measuring the flow of water from faucets and sinks on the Oregon Military Department's Camp Rilea training base, water efficiency experts are determining how the site can get closer to net-zero water.

I got a chance to talk with a water efficiency engineer at the Pacific Northwest National Lab last week.

The water balance study for Camp Rilea showed much of the water use is going toward plumbing in the barracks for trainees.

“It’s really important to do the water balance analysis,” she said. “What the water balance does is it helps a facility or a site understand the disaggregation of their water use by equipment type. If you don’t do that you don’t know where to target your efficiency measures.”

McMordie is now working with a contractor called Water Savers LLC on the next key step, which is outlining places where the training base can become more water efficient – by adding high-efficiency toilets, shower heads and faucets, for example.

“We’re right in the beginning of that,” McMordie said. “We’re running a life-cycle cost analysis to measure how much the product technology is going to save over the life of the project. Not just the initial cost, but how much Camp Rilea will be saving over the entire life.”

One water-saving measure that could be an option for Camp Rilea is a weather-based control system that monitor moisture and precipitation before watering.

“It uses that data to understand how much moisture has hit that plant and how much water is needed by the plant to stay healthy,” said McMordie.

To figure out how much water can be saved by upgrading to high-efficiency plumbing, McMordie’s team has to figure out how much water is flowing through faucets, shower heads and toilets right now. To do that they actually use special tools that measure the rate of flow. They apply that rate to the total water use for the various locations.

“We know the general water patterns of people. How many people use the restroom, and how often. How long their showers are,” she said. “And we calculate water use based on the population. We estimate the water use in toilets and urinals by the rate of flush and how long it takes for the flush to finish. It’s not an exact science, but it gives us an estimate.”

PNNL has a larger contract with the Army to help build roadmaps to net-zero water at seven locations across the country.

Camp Rilea’s closed-loop water supply and recycling system goes a long way toward net-zero water, said McMordie.

Normally, the cost savings from water efficiency measures are calculated based on the water rates. That means if the water rate is low, it’s harder to make the case for upgrading to high-efficiency plumbing.

But in Camp Rilea’s case, the military is pumping and treating its own water. And there are definite costs associated with that.

“We’re just helping them reduce their demand for water,” McMordie said. “That determines how much they have to pump and treat.”

EarthFix is a public media partnership of Oregon Public Broadcasting, Idaho Public Television, KCTS9 Seattle, KUOW Puget Sound Public Radio, Northwest Public Radio and Television, Jefferson Public Radio, KLCC and the Corporation for Public Broadcasting.